1. Field of the Invention
The present invention relates to a relief valve, and more particularly, to such a valve that is used to extract a liquid from a sealed container through the injection of pressurized gas.
2. Description of the Related Art
Applicant believes that the closest reference corresponds to U.S. Pat. No. Des. 226,431 issued to Embury. However, it differs from the present invention because it fails to provide for means to extract liquids that may be contained within the container whose pressure it is intended to control. The same thing can be said of U.S. Pat. No. 3,189,040 issued to Johnson. None of these references are concerned with the exposure of workers to the pollutants that exist inside the cases for transformers nor do they even suggest how to facilitate the extraction of specimens of the liquid, typically oil, in which the transformer coil is submerged. When transformer's are serviced with conventional procedures there is a down time problem because the seals of the case need to be tested. This requires that the pressure relief valve be replaced with a time valve type so that it can be pressurized. Afterwards, the relief valve is replaced.
It is known that these transformer cases require constant testing making it necessary to open the cases periodically with the consequent exposure to the worker and to the environment of highly toxic pollutants. See enclosed the relevant pages of the Federal Register of May 31, 1979: Polychlorinated Biphenyis (PCB); Criteria Modification, Hearings, which is incorporated hereto by reference. The present invention permits ready access to the liquid inside these sealed containers with a minimum of exposure, and it does not require replacement of valves thereby minimizing down time.
Other patents describing the closest subject matter provide for a number of more or less complicated features that fail to solve the problem in an efficient and economical way. None of these patents suggest the novel features of the present invention.